Beam compass



United States Patent 3,103,070 BEAM COMPASS Olin L. Looker, Stoclrland, Ill. Filed Feb. 13, 1962, Ser. No. 173,019 2 Claims. (Cl. 33-27) This invention relates to drafting instruments and more particularly to an instrument for describing arcuate figures, such as a beam compass.

The currently available commercial devices designed for use in describing large arcuate figures require set screw adjustments when it is necessary to change the radius of the are described. The standard beamcompass cornprises a fixed pivot point and a movable scribing instrument holder which may be positioned along the longitudinal extent of the beam only after loosening the appropriate set screws, moving the scribing instrument holder to the desired position, and then tightening the set screws. Such a device does not lend itself to rapid and convenient radius adjustments. Furthermore, such adjustments may often prove inaccurate because the scribing instrument holder may be moved from its measured position in the process of tightening the set screws.

It is a primary object of this invention to provide a new and improved beam compass.

It is another object of this invention to. provide a new and improved beam compass which may be rapidly and easily adjusted for describing arcs of different radii.

It is yet another object of this invention to provide a new and improved beam compass which may be accurately adjusted in a novel manner to describe an arc of a desired radius. i

It is still another object of this invention to provide a new and improved beam compass which does not require the use of set screws toposition a scribing instrument holder at any point thereon.

It is a further object of this invention to provide a new and improved beam compass adapted to be used with a common wooden graphite :drafting pencil.

It is a still further object of this invention to provide a new and improved beam compass comprising a beam member and a scribing instrument holder movable longitudinally thereof, the scribing instrument holder having means for coarse and fine adjustment of the holder for any point on the beam not requiring the use of locking or unlocking elements to secure the holder at a given point on the beam.

Further features and advantages will be readily apparent from the following specification and from the drawings, in which:

FIGURE 1 is a side elevational view in partial section of an embodiment of this invention;

FIGURE 2 is a top plan view of the device of FIG- URE 1;

FIGURE 3 is a side elevational view taken from the opposite side of the view shown in FIGURE 1; and

FIGURE 4 is a section view taken along the line 44 of FIGURE 1.

In the illustrated embodiment of my invention the beam compass includes a beam 1t} which is a generally rectangular elongate box like member of rigid material such as aluminum or the like. A pivot in the form of a pin 12 is secured at one end of the beam by means of a set screw 14 providing the beam with a pivot point about which an arc may be described. A scribing instrument holder 16 is positioned on the beam for movement along the longitudinal extent thereof. A scribing instrument, such as a pencil, 13 is mounted in the scribing instrument holder for providing the device with means for describing an are when the device is pivoted about 3,103,070 Patented Sept. 10, 1963 member having a V-shaped configuration. in plan. It consists of a pair of parallel bifurcated legs with individual leg portions 20, 22, 24 and 26 which extend diagonally rearward from a central base 28. The lower legs 22 and 26 extend across the bottom of the beam 10 and the upper legs 20 and 24 extend across the top of the beam 10. Each of the pairs of legs supportsone of a pair of rollers 30 and 32 in generally parallel relation to the base 28. The rollers 30 and 32 extend from the top to the bottom of the beam 10 and are in rolling contact with the side of the beam 10 opposite the base 28 of the holder 16. I j

The interior sides of the central base 28 describes a 60 angle in plan. The pencil 18 is secured within the holder 16 between the beam 10 and the: base of the holder 28. This provides the interior of the base with surfaces on the inside to be in facial engagement with faces 18a and 18b of the conventional hexagonal shape drafting pencil and insures that face will be in fiat facial contact with the side of the beam 10. The bifurcated legs extend from the common base 28 and fiare out- Wardly at a greater than 60 angle relative to each other. The legs 29, 22, 24 and 26 are closely spaced in relation tothe top and bottom surfaces of the beam 14) and thus serve to secure the holder against any tilting movement with respect to the longitudinal axis of the beam. Also because the legs-flare outwardly from the base at a greater than 60 angle the legs tend to extend in a direction generally lengthwise of the beam 10 and thus restrain the holder from tilting about the beam in a plane generally transverse to the longitudinal axis ofthe beam. The spring holder 16 tightly embraces the pencil 18 preventing any lateral or vertical movement of the pencil within the holder. Though the illustrated embodiment shows a conventional wooden drafting pencil secured within the holder 16 it is to be understood that mechanical drafting pencils are capable of use with this instrument also.

The rollers 30 and 32 frictionally hold the holder 16 against the beam .and provide finger grip means for moving the pencil holder lengthwise of the beam. The rollers are spaced apart a sufficient distance to spring the holder 16 from its normal configuration when the pencil is in place. The movement of the holder 16, as well as the frictional retention of the holder against the beam 10 is facilitated by the fact that, in the case of a conventional wooden drafting pencil, the pencil is held with a flat face 180 against the side of the beam 10 as previously mentioned. The holder 16 may be disengaged from the beam by rolling it off the end opposite the pin 12. This causes the pencil 18 to drop out and allow the insertion of another pencil of difierent hardness if desired. To make the unit reversible for left or right hand operation the holder 16 is merely placed back on the beam 10 with the pencil on the appropriate side thereof. To reset the holder on the beam it is positioned at the end of the beam opposite the pivot with one roller against the side of the beam and the other roller on the end. A pencil is then placed between the side of the beam and the interior of the base and the other roller is rolled over the end of the beam and against the same side of the beam as the first mentioned roller.

The rollers 30 and 32 provide a sufiicient frictional force to maintain the holder 16 at any preselected point along the length of the beam 10. Thus no separate locking means such as set screws are necessary to secure the holder 16 at a given point. To move the holder 16 along the beam 10 the rollers 30 and 32 are merely pushed with thumb or finger pressure to the desired position. A feature of this device is that it is capable of coarse and fine adjustment. By applying finger or thumb pressure against the rollers to the exterior of the legs, the

spring action of the holder 16 is opposed, reducing the amount of force with which the holder 16 and pencil 18 are held against the beam 10. This provides easier movement of the holder 16 along the beam 10. When finger or thumb pressure is applied on the side of the rollers within the interior of or between the legs, the spring action of the holder 16 is assisted, tending to slightly increase the force with which the holder 16 and the pencil 18 are held against the beam 10. This increases the force necessary for moving the holder 16 along the beam and aids in making fine adjustments for positioning the holder 16. For rapidly traversing the holder 16 along the beam 10 the user may grasp the beam in one hand and grasp the pencil with his other hand, and quickly and easily slide the holder to any desired position.

In the illustrated embodiment of this invention the beam 10 is a generally elongate rectangular box shaped member. The beam may be made of any desired length, up to several feet if necessary, depending on the intended usage of the device. The suggested configuration of the beam provides it with two pairs of opposed parallel surfaces. One pair of surfaces provides a base of travel for the rollers and the oppositely positioned pencil. The other pair of surfaces is closely straddled by the bifurcated legs of the holder. This gives the holder stability against tilting relative to the longitudinal axis of the beam as well as in a plane generally transverse to the longitudinal extent of the beam. It is to be understood that relation of the beam surfaces to the holder components could be accomplished by other beam configurations. For example, a H-shaped structure or I beam possesses the requisite two pairs of parallel opposed surfaces and could be adapted for use as .a beam member for the holder member of this invention.

This invention provides a beam compass which may be rapidly and accurately positioned to any given radius and held in the selected position without the use of any separate locking devices. The pencil holder is easily moved along the length of the beam and has means for coarse and fine adjustment. Furthermore, a conventional wooden graphite drafting pencil may be used for the beam compass. These pencils are easily removed from the compass so that they may be replaced With pencils of different hardness if desired. The compass is also capable of use with a mechanical drafting pencil.

The foregoing detailed description has been given for the clearness of understanding only and no unnecessary limitations should be understood therefrom for some modifications will be obvious to those skilled in the art.

I claim:

l. A draftsmans beam compass, comprising: a rigid beam having upper and lower parallel surfaces and connecting surfaces at right angles thereto; pivot center means secured at one end of said beam for anchoring said beam for swinging about said pivot as a center; and a scribing instrument holder carried by said beam for positioning a scribing instrument a fixed distance from said pivot means, said holder being a unitary spring member, being generally V-shaped in plan and having a base and two bifurcated legs extending diagonally therefrom, each leg closely straddling said beam therebetween, said holderincluding a pair of rollers journalled in the terminal ends of each leg and being rotatably supported thereby in upright fashion against the side of the beam opposite said base, said rollers being spaced apart, one on each side of the center of said scribing instrument, so that the center of the rollers and the scribing instrument describe a triangle in plan, said base being shaped to conform to selected surfaces on said scribing instruments of different shapesand directly force the scribing instrument against an upright surface on said beam, said spring being sprung from its at rest configurationwhen so hold ing a scribing instrument with said rollers engaging the opposite upright surface of said beam whereby said spring holds said scribing cinst-rument in frictional engagement with said beam to lock said instrument against undesired relative movement.

2. The device of claim 1 wherein said base of said holder describes a degree angle in plan and said bifurcated legs flare outwardly therefrom generally lengthwise of said beam for locking said holder on said beam against tilting about the beam as an axis.

References Cited in the file of this patent UNITED STATES PATENTS 1,240,853 Jachimowicz Sept. 25, 1917 2,106,398 Bartusch Jan. 25, 1938 FOREIGN PATENTS 155,970 Great Britain Jan. 6, 1921 

1. A DRAFTSMAN''S BEAM COMPASS, COMPRISING: A RIGID BEAM HAVING UPPER AND LOWER PARALLEL SURFACES AND CONNECTING SURFACES AT RIGHT ANGLES THERETO; PIVOT CENTER MEANS SECURED AT ONE END OF SAID BEAM FOR ANCHORING SAID BEAM FOR SWINGING ABOUT SAID PIVOT AS A CENTER; AND A SCRIBING INSTRUMENT HOLDER CARRIED BY SAID BEAM FOR POSITIONING A SCRIBING INSTRUMENT A FIXED DISTANCE FROM SAID PIVOT MEANS, SAID HOLDER BEING A UNITARY SPRING MEMBER, BEING GENERALLY V-SHAPED IN PLAN AND HAVING A BASE AND TWO BIFURCATED LEGS EXTENDING DIAGONALLY THEREFROM, EACH LEG CLOSELY STRADDLING SAID BEAM THEREBETWEEN, SAID HOLDER INCLUDING A PAIR OF ROLLERS JOURNALLED IN THE TERMINAL ENDS OF EACH LEG AND BEING ROTATABLY SUPPORTED THEREBY IN UPRIGHT FASHION AGAINST THE SIDE OF THE BEAM OPPOSITE SAID BASE, SAID ROLLERS BEING SPACED APART, ONE ON EACH SIDE OF THE CENTER OF SAID SCRIBING INSTRUMENT, SO THAT THE CENTER OF THE ROLLERS AND THE SCRIBING INSTRUMENT DESCRIBE A TRIANGLE IN PLAN, SAID BASE BEING SHAPED TO CONFORM TO SELECTED SURFACES ON SAID SCRIBING INSTRUMENTS OF DIFFERENT SHAPES AND DIRECTLY FORCE THE SCRIBING INSTRUMENT AGAINST AN UPRIGHT SURFACE ON SAID BEAM, SAID SPRING BEING SPRUNG FROM ITS AT REST CONFIGURATION WHEN SO HOLDING A SCRIBING INSTRUMENT WITH SAID ROLLERS ENGAGING THE OPPOSITE UPRIGHT SURFACE OF SAID BEAM WHEREBY SAID SPRING HOLDS SAID SCRIBING INSTRUMENT IN FRICTIONAL ENGAGEMENT WITH SAID BEAM TO LOCK SAID INSTRUMENT AGAINST UNDESIRED RELATIVE MOVEMENT. 